Xintang, China (CNN) -- Noisy traffic and bustling crowds returned to the streets of Xintang on Friday after days of rioting by migrant workers, but security remained heavy in this industrial town in southern China that produces almost half of the jeans sold in the United States.

Police and guards were manning checkpoints at major intersections, questioning some drivers. Anti-riot police patrolled the streets as propaganda vans touted the importance of stability. Fire trucks with high-pressure water cannons stood ready to deal with potential unrest.

Authorities have arrested 19 men, including nine teenagers, on charges related to the riots, the local government said on its website.

Outside the Longjiafu supermarket, where a scuffle between two street vendors and town officials triggered the unrest on June 10, people were reluctant to recount the incident to foreign reporters.

Witnesses and media reports said local officials beat up a pregnant migrant worker and her husband, pushing the woman to the ground. Mass protests ensued, quickly spiraling to violent clashes with government forces that spread to other parts of Xintang, a city of 400,000 residents, almost half of them migrant workers.

Photos posted online showed torched police cars and government offices by angry demonstrators. Witnesses told CNN of looting and other violence at night. Anti-riot police and paramilitary troops were sent in, reportedly using tear gas to disperse the crowds.

Although local authorities put the number of "troublemakers" at several hundred, tens of thousands are said to have taken to the streets during three days of riots, some of the worst seen in China in years.

Zhang Jihe, who owns a jeans factory that churns out up to one million pairs a year, said he hoped to see things return to normal soon, especially in light of an already-tough business climate.

"Our production cost has gone up," Zhang said. "Workers' wages are higher, fabric and other materials are pricier."

At a labor market next to Xintang High School, now a makeshift anti-riot command center, migrant workers also saw a darker future in this export-oriented town.

"Factories are not getting enough orders," said Tan Zhijian, 33, who has worked in clothing factories in Xintang for 17 years. "Many owners owe workers back pay. Some just run away."

Although they did not get involved in the riots, the workers at the job market say they share the frustrations of the street vendors whose treatment by officials unleashed the turmoil.

For years, booming industries in southern China, particularly Guangdong province where Xintang is located, have attracted millions of migrant workers from poor rural provinces looking to find factory jobs and a better life.

Mirroring the rest of the country, a slowdown in economic growth here is now stoking social tensions in various dimensions --- rural versus urban, ethnic minority against majority, and haves versus have have-nots.

"The people who were being squeezed now feel like they are being squeezed even more, to the point where they can't bear it anymore," said Patrick Chovanec, a political analyst with Tsinghua University in Beijing. He said China's one-party system fails to provide people with a proper mechanism to air grievances or resolve disputes.

"When those violent outbreaks do take place, especially in light of what's happened with the Arab Spring, the government feels the need to simply throw in the use of force," he added.

Back in Xintang, authorities are taking no chances. Propaganda officials stopped CNN from filming on the streets and questioned the journalists in their office for an hour. The team was ordered to leave the town just as night was falling --- the time local residents have said when the risk of rioting is highest.